Title :
Performance evaluation of interpolated average CT for PET attenuation correction in different lesion characteristics
Author :
Ho, Cobie Y. T. ; Tao Sun ; Tung-Hsin Wu ; Mok, G.S.P.
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Macau, Macau, China
fDate :
Oct. 27 2013-Nov. 2 2013
Abstract :
Previously we demonstrated the effectiveness of the interpolated average CT (IACT) for attenuation correction (AC) in PET in simulations and clinical patients. This study aims to evaluate the performance of IACT for thoracic lesions with different sizes, uptake ratios and locations. The XCAT phantom was used to simulate noisy 18F-FDG distribution based on the clinical count level with respiratory motion amplitude of 2 cm and 3 cm. The average activity and attenuation maps represented static PET and cine average (CACT) respectively. IACT was generated by the end-inspiration and end-expiration phases of the attenuation maps (HCT-in and HCT-ex) using deformable registration method. Spherical 10 mm and 20 mm lesions were simulated at 4 locations individually, including the lower left lung (LLL), lower right lung (LRL), middle right lung (MRL) and upper right lung (URL). Four target-to-background ratios (TBR), including 4:1 and 8:1 for respiratory motion of 2 cm, 6:1 and 12:1 for respiratory motion of 3 cm, were modeled. The noisy sinograms with attenuation modeling were generated and reconstructed with different AC maps by STIR (Software for Tomographic Image Reconstruction), using OS-EM with up to 300 updates. Normalized mean square error (NMSE), mutual information (MI) and TBR were analyzed. The NMSE and MI results showed that PETCACT and PETIACT were more similar to the original phantom as compared to PETHCTs. For TBRs, the differences between CACT/IACT and HCTs AC were more significant for lesions in the lower lung with PETHCT-ex showed higher TBR and PETHCT-in showed lower TBR as compared to PETCACT/PETIACT for all lesion sizes, uptake ratios and respiratory motion amplitudes. The TBRs for 10 mm lesion were more difficult to be recovered in all AC schemes. Better lesion localization and more stable quantitation for different lesion characteristics make IACT a good alternate for- AC as compared to conventional HCT/CACT.
Keywords :
computerised tomography; drugs; image reconstruction; image registration; information theory; interpolation; lung; mean square error methods; medical image processing; phantoms; physiological models; pneumodynamics; positron emission tomography; AC maps; CACT/IACT; HCT/CACT; HCTs AC; IACT generation; IACT performance evaluation; MI analysis; NMSE analysis; OS-EM; PET attenuation correction; PETCACT/PETIACT; PETHCT-ex; PETHCT-in; PETHCTs; STIR method; TBR analysis; XCAT phantom; attenuation map end-expiration phases; attenuation map end-inspiration phases; attenuation maps; attenuation modeling; average activity; cine average CT; clinical count level; deformable registration method; interpolated average CT; lesion characteristics; lesion localization; lower left lung location; lower lung lesions; lower right lung location; middle right lung location; mutual information analysis; noisy 18F-FDG distribution simulation; noisy sinogram generation; noisy sinogram reconstruction; normalized mean square error analysis; respiratory motion amplitude; respiratory motion model; size 10 mm; size 20 mm; software for tomographic image reconstruction method; spherical lesion simulation; stable lesion characteristic quantitation; static PET; target-to-background ratios; thoracic lesion locations; thoracic lesion sizes; thoracic lesion uptake ratios; upper right lung location; Attenuation; Computed tomography; Image reconstruction; Lesions; Lungs; Positron emission tomography; Standards;
Conference_Titel :
Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2013 IEEE
Conference_Location :
Seoul
Print_ISBN :
978-1-4799-0533-1
DOI :
10.1109/NSSMIC.2013.6829262
